Read an Excerpt from A New IBS Solution

Irritable bowel syndrome (IBS) is the most common chronic medical
condition and is characterized by abdominal pain, bloating, and
altered bowel habits. Although there is some variation from study
to study and country to country, up to 20% of a given population
appears to be affected by this condition. In addition, unlike other
chronic conditions such as heart disease, IBS commonly affects all
ages. In fact, studies have shown that patients with IBS have a
lower quality of life than those with heart disease or other chronic
medical conditions. Despite these facts, developments that may identify
causes for IBS have happened only recently.

The progress to find a cause for IBS can hardly be called a race.
The nature of the illness has interfered with that progress; most
patients with IBS find it difficult to discuss their bowel problems
with others, and often suffer in silence. This may be in part because
the media tends to ridicule patients with IBS or other digestive
conditions such as lactose intolerance. All of these factors lead
to social isolation and continued unwillingness to discuss the condition,
further contributing to the patients’ lower quality of life
and the public’s ignorance of IBS. One reason for our lack
of knowledge about IBS is the lack of funding for research into
its cause and treatment. Since IBS is not a fatal illness, it is
not given priority for research funding. As a result, researchers
who wish to unravel the IBS puzzle struggle to secure resources;
fundraising takes up time those physicians would otherwise have
for treating patients. Moreover, only a handful of researchers in
the U.S. are working to identify a cause for IBS. The result is
that most physicians continue to have a poor understanding about
IBS. Often, when a disease is not clearly understood, the first
inclination is to link the disease with the psychological condition
of the patient. There are many historical examples of such thinking.
In the 1970’s, there was much discussion about the cardiac
risk posed by having a “type A” personality. We now
understand heart disease in a completely different way and this
reference is no longer part of the medical doctrine.

In another example, stress was thought to be the main cause of
stomach ulcers until the discovery of the bacteria Helicobacter
pylori as the most common culprit. With the inability of scientists
to pinpoint the causes of IBS, the patients have fallen victim to
psychological scrutiny and are often stigmatized as a result. In
some cases this stigma makes it difficult for IBS sufferers to obtain
insurance policies, especially disability insurance.

To be fair, it is well known that a history of severe psychological
trauma can lead to changes in bowel function. It is also understood
that stress can influence the degree of symptoms in some IBS sufferers.
However, now it is known that in most cases stress and psychological
problems neither cause nor are associated with IBS. While this conclusion
should be a victory for those with IBS, the stigma remains since
the misconceptions run deep in the grass-roots medical community.

Many factors have contributed to the declarations of IBS as being
more than psychological. For example, in non-university-based medical
studies, the psychological profile of IBS patients is no different
than the rest of the community. This discovery was paralleled by
research contributing to the development of four new theories in
IBS.

The discovery of altered pain perception in the gut was the first
of four key findings. In the 1990’s studies demonstrated that
IBS patients experienced gut pain at much lower thresholds than
the general population. In other words, what would not be considered
painful to the gut in normal subjects was perceived as painful in
IBS patients. This led to innovative studies looking at pain processing
in the gut and its transmission to the brain, or the “Brain-Gut
Axis.” Brain imaging has since shown that IBS patients respond
differently to pain; locations of the brain not otherwise activated
by pain were being turned on in IBS. This work had several limitations;
the techniques for measuring brain imaging required a high level
of expertise and yielded inconsistent results among studies. Also,
for patients, this concept has not easily translated into a better
understanding of the causes and treatment of IBS.

One negative outcome of these findings was the initial marrying
of these pain and brain findings to the older psychological theory
of IBS. This union led investigators to consider antidepressant
medications as a potential remedy. Since some antidepressants (especially
tricyclic antidepressants such as amitryptyline) have also been
shown to have numbing effects on the spine pain fibers (nerves),
the fit was too tempting. While the ill effects of widespread antidepressant
use had some in the scientific community concerned, studies showed
that antidepressants could slow down bowel movements. Thus the concept
that any antidepressant could work began to take hold. The ultimate
consequence is that antidepressants have been a mainstay of IBS
treatment. Shortly after the discovery of heightened sensation in
the gut in IBS, others were taking a different scientific approach.
One sentiment was that IBS was difficult to define because the disease
was really a mixed group of conditions. The division of IBS into
subcategories could in theory simplify its definition, making the
causes more apparent. This approach led to the second theory of
IBS, in which IBS is a group of disorders, with the dominant symptom
defining each group. IBS with diarrhea as the main symptom would
be labeled “diarrhea-predominant IBS”; and if constipation
was the main feature, the label would read “constipation-predominant
IBS.” Efforts were also made to provide a clear definition
of IBS. From this thinking was born what is now referred to as the
Rome Criteria.

Studies then emerged showing that for IBS patients suffering from
constipation, intestinal movements were slower compared with normal
controls. In contrast, in IBS patients suffering from diarrhea,
the gut appeared to propel its contents too fast. Based on this,
drug companies began to search for the chemicals produced by the
gut that control its movement. A key chemical is serotonin, secreted
by cells that line the gut wall. When food enters the area, serotonin
is released, causing the gut to contract in a special fashion called
peristalsis. Peristalsis in this context is a forward movement or
spreading of gut contents such as food down the gut. On a simplified
level, if there is too much serotonin there is too much movement;
not enough and the gut is slower. Some IBS studies demonstrated
this connection between serotonin levels and gut movement, which
became the basis for a new class of drugs that block (alosetron,
cilansetron, granisetron) or augment (tegaserod) the sites of action
of serotonin.

The third theory of IBS stems from a pattern that investigators
began to recognize among patients with IBS who had suffered attacks
of acute diarrhea. Approximately 20% of IBS sufferers declare that
their bowel habits were perfectly normal until such an attack. In
most cases the patients recall the incident as a clear case of food
poisoning, while in many other instances the acute diarrhea began
on a trip abroad. Even after the acute episode of diarrhea subsides,
the bowel habits never return to normal. In light of this history,
clinicians aggressively investigated the stool for infective agents
but found nothing, often years after the initial event. The recognition
of this symptom complex has led researchers from Europe and Canada
to study food poisoning cases. Now, most researchers agree that
a certain proportion of food poisoning cases will lead to perpetual
IBS-like symptoms. This idea of IBS being precipitated by an intestinal
infection was termed “post-infectious IBS.”

The final, most recent theory defines IBS as a bacterial disease.
Patients with IBS inevitably complain of gas and bloating. While
this was once considered a major hallmark of IBS, the failure to
understand this component led investigators in the 1980’s
to emphasize what was more easily grasped; hence the focus on diarrhea
and constipation. Still, even as most members of the scientific
community were distracted by the emphasis on bowel function, others
investigated the bacterial component of IBS. In the 1990’s,
research showed that IBS patients (over a given time) produced 5
times more gas than did people without IBS. Since the only source
of those gases was bacterial, the initial presumption was that IBS
patients had excessive bacteria in the colon, where bacteria were
expected to be. Subsequent studies showed that IBS patients had
excessive quantities of gas in the small bowel; these data were
the catalyst for studying small bowel bacteria in IBS.

Normally the small intestine contains a very small quantity of
bacteria. In published studies, indirect measures of small bowel
bacteria suggest that 84% of IBS sufferers have excessive quantities
of bacteria typically found in the colon.

Intuitively, higher bacterial levels in the small bowel, where
absorption takes place, would ferment the nutrients from the food
into gas. Further work in this area has determined that these bacteria
could produce both constipation and diarrhea, depending on the types
of bacteria that have moved into the small bowel. These results
have led to studies showing that antibiotics can almost completely
relieve IBS symptoms if successful in eliminating the intestinal
bacteria. This is called the “bacterial overgrowth theory
of IBS.”

This book takes you through the evolution of thinking in IBS in
a way that can be easily understood. The research is often complex
even for those in the field; physicians and patients alike may get
lost trying to understand the quagmire of opinions and research
findings. In the desire for help, along with frustration with their
physicians’ limited understanding of how to treat IBS, patients
have turned to alternative therapies such as probiotics. While some
of these therapies have positive results, others are not as helpful
and in some rare cases may be detrimental. These too will be discussed.
While the initial chapters focus on how the theories of IBS diverge,
the final chapters will show how the theories converge into a unifying
hypothesis, and will give an indication of where IBS developments
are heading in the future.

Information on this site is provided for informational
purposes only and is in no way intended to be a substitute for medical
consultation. If you have questions or concerns about any medical
problem or health condition, you should consult your own physician.